1. Field of Invention
The present invention relates to techniques for determining a flow rate of a fluid flowing in a pipe; and more particularly related to techniques for determining a flow rate in a pipe, tank, vessel or container using a combined tomographic and SONAR-based and modeled signal processing technique.
2. Description of Related Art
Known SONAR processing typically relies on acoustic monitoring of dynamic pressure variations along a flow pipe caused by the flow, and SONAR processing of this information to yield flow rate.
Recently, several approaches to visualize a cross section of a multi-phase flow have been devised based on Electrical Resistance Tomography (ERT), or often refereed to as Electrical Impedance Tomography (EIT), or Electrical Capacitance Tomography (ECT). The former is generally used for conducting fluids, where the latter is used in non-conducting fluids. Tomographic techniques or approaches based on the use of ERT, EIT and ECT are becoming widely exploited in industrial processes for the analysis of mixing in multi-phase flows, liquid interfaces and liquid-froth layers for example.
These tomographic approaches allow visualization of a flow cross-section, and can be a powerful tool to analyze multi-phase flows, mixing, and flow stratification, etc. By way of example, FIG. 1a shows a generic configuration for ‘in-pipe’ tomographic imaging using multiple electrodes around the pipe wall; and FIG. 1b shows a type of image created using tomographic analysis of flows.
It has been shown that by performing tomographic processing at two (2) planes along a flow tube, a cross-sectional tomographic image formed at a first plane is correlated to that formed at a second plane to allow flow rate determination of the phase fractions. This known technique requires a reconstitution of a full tomographic image at each of the two planes, which involves a lot of signal processing.
In tomographic imaging, electrical probing is typically conducted via multiple electrodes around the pipe wall.